Interferon-stimulated genes inhibit caprine parainfluenza virus type 3 replication in Madin-Darby bovine kidney cells

Differentially Expressed miRNA Profiles in Serum-Derived Exosomes from Cattle Infected with Lumpy Skin Disease Virus

Exosomal miRNAs from individual cells are crucial in regulating the immune response to infectious diseases. In this study, we performed small RNA sequencing (small RNA-seq) analysis to identify the expressed and associated exosomal miRNAs in the serum of cattle infected with lumpy skin disease virus (LSDV). Cattle were infected with a 106.5 TCID50/mL LSDV Vietnam/HaTinh/CX01 (HT10) strain and exosomal miRNA expression in the serum of infected cattle was analyzed using small RNA sequencing (small RNA-seq). We identified 59 differentially expressed (DE) miRNAs in LSDV-infected cattle compared to uninfected controls, including 18 upregulated and 41 downregulated miRNAs. These 59 miRNAs were used to predict 7656 target genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the target genes were enriched in several biological processes and pathways associated with viral replication, immune response, virus-host interactions, and signal transduction. Additionally, we identified 708 potentially novel cattle miRNAs corresponding to 710 genomic loci. The transcription levels of five miRNA genes (bta-miR-11985, bta-miR-1281, bta-miR-12034, bta-miR-let-7i, and bta-miR-17-5p) were validated using reverse transcription quantitative real-time PCR, showing consistency with the small RNA-seq results. Overall, these findings provide significant insights into the immune and protective responses during LSDV infection in cattle, offering valuable information on identifying new biomarkers and understanding the pathogenesis of LSDV.

You Shall Not Pass: MX2 Proteins Are Versatile Viral Inhibitors

Myxovirus resistance (MX) proteins are pivotal players in the innate immune response to viral infections. Less than 10 years ago, three independent groups simultaneously showed that human MX2 is an interferon (IFN)-stimulated gene (ISG) with potent anti-human immunodeficiency virus 1 (HIV-1) activity. Thenceforth, multiple research works have been published highlighting the ability of MX2 to inhibit RNA and DNA viruses. These growing bodies of evidence have identified some of the key determinants regulating its antiviral activity. Therefore, the importance of the protein amino-terminal domain, the oligomerization state, or the ability to interact with viral components is now well recognized. Nonetheless, there are still several unknown aspects of MX2 antiviral activity asking for further research, such as the role of cellular localization or the effect of post-translational modifications. This work aims to provide a comprehensive review of our current knowledge on the molecular determinants governing the antiviral activity of this versatile ISG, using human MX2 and HIV-1 inhibition as a reference, but drawing parallelisms and noting divergent mechanisms with other proteins and viruses when necessary.

Free ISG15 Inhibits the Replication of Peste des Petits Ruminants Virus by Breaking the Interaction of Nucleoprotein and Phosphoprotein

Peste des petits ruminants virus (PPRV) causes a highly contagious disease in small ruminants and severe economic losses in developing countries. PPRV infection can stimulate high levels of interferon (IFN) and many IFN-stimulated genes (ISGs), such as ISG15, which may play a key role in the process of viral infection. However, the role of ISG15 in PPRV infection and replication has not yet been reported. In this study, we found ISG15 expression to be significantly upregulated after PPRV infection of caprine endometrial epithelial cells (EECs), and ISG15 inhibits the proliferation of PPRV. Further analysis showed that free ISG15 could inhibit PPRV proliferation. Moreover, ISG15 does not affect the binding, entry, and transcription but does suppress the replication of PPRV. A detailed analysis revealed that ISG15 interacts and colocalizes with both viral N and P proteins and that its interactive regions are all located in the N-terminal domain. Further studies showed that ISG15 can competitively interact with N and P proteins and significantly interfere with their binding. Finally, through the construction of the C-terminal mutants of ISG15 with different lengths, it was found that amino acids (aa) 77 to 101 play a key role in inhibiting the binding of N and P proteins and that interaction with the P protein disappears after the deletion of 77 to 101 aa. The present study revealed a novel mechanism of ISG15 in disrupting the activity of the N⁰-P complex to inhibit viral replication. IMPORTANCE PPRV, a widespread and fatal disease of small ruminants, is one of the most devastating animal diseases in Africa, the Middle East, and Asia, causing severe economic losses. IFNs play an important role as a component of natural immunity against pathogens, yet the role of ISG15, an IFN-stimulated gene, in protecting against PPRV infection is currently unknown. We demonstrated, for the first time, that free ISG15 inhibits PPRV proliferation by disrupting the activity of the N⁰-P complex, a finding that has not been reported in other viruses. Our results provide important insights that can further understand the pathogenesis and innate immune mechanisms of PPRV.

Inferred Causal Mechanisms of Persistent FMDV Infection in Cattle from Differential Gene Expression in the Nasopharyngeal Mucosa

Foot-and-mouth disease virus (FMDV) can persistently infect pharyngeal epithelia in ruminants but not in pigs. Our previous studies demonstrated that persistent FMDV infection in cattle was associated with under-expression of several chemokines that recruit immune cells. This report focuses on the analysis of differentially expressed genes (DEG) identified during the transitional phase of infection, defined as the period when animals diverge between becoming carriers or terminators. During this phase, Th17-stimulating cytokines (IL6 and IL23A) and Th17-recruiting chemokines (CCL14 and CCL20) were upregulated in animals that were still infected (transitional carriers) compared to those that had recently cleared infection (terminators), whereas chemokines recruiting neutrophils and CD8+ T effector cells (CCL3 and ELR+CXCLs) were downregulated. Upregulated Th17-specific receptor, CCR6, and Th17-associated genes, CD146, MIR155, and ThPOK, suggested increased Th17 cell activity in transitional carriers. However, a complex interplay of the Th17 regulatory axis was indicated by non-significant upregulation of IL17A and downregulation of IL17F, two hallmarks of TH17 activity. Other DEG suggested that transitional carriers had upregulated aryl hydrocarbon receptor (AHR), non-canonical NFκB signaling, and downregulated canonical NFκB signaling. The results described herein provide novel insights into the mechanisms of establishment of FMDV persistence. Additionally, the fact that ruminants, unlike pigs, produce a large amount of AHR ligands suggests a plausible explanation of why FMDV persists in ruminants, but not in pigs.

Research Progress on Emerging Viral Pathogens of Small Ruminants in China during the Last Decade

China is the country with the largest number of domestic small ruminants in the world. Recently, the intensive and large-scale sheep/goat raising industry has developed rapidly, especially in nonpastoral regions. Frequent trading, allocation, and transportation result in the introduction and prevalence of new pathogens. Several new viral pathogens (peste des petits ruminants virus, caprine parainfluenza virus type 3, border disease virus, enzootic nasal tumor virus, caprine herpesvirus 1, enterovirus) have been circulating and identified in China, which has attracted extensive attention from both farmers and researchers. During the last decade, studies examining the etiology, epidemiology, pathogenesis, diagnostic methods, and vaccines for these emerging viruses have been conducted. In this review, we focus on the latest findings and research progress related to these newly identified viral pathogens in China, discuss the current situation and problems, and propose research directions and prevention strategies for different diseases in the future. Our aim is to provide comprehensive and valuable information for the prevention and control of these emerging viruses and highlight the importance of surveillance of emerging or re-emerging viruses.

Temporal Dynamics of the Ruminant Type I IFN-Induced Antiviral State against Homologous Parainfluenza Virus 3 Challenge In Vitro

Viruses have evolved diverse strategies to evade the antiviral response of interferons (IFNs). Exogenous IFNs were applied to eliminate the counteracting effect and possess antiviral properties. Caprine parainfluenza virus 3 (CPIV3) and bovine parainfluenza virus type 3 (BPIV3) are important pathogens associated with respiratory diseases in goat and cattle, respectively. To explore the feasibility of type I IFNs for control of CPIV3 and BPIV3 infection, the activated effects of IFN-stimulated genes (ISGs) and the immunomodulation responses of goat IFN-α were detected by transcriptomic analysis. Then, the antiviral efficacy of goat IFN-α and IFN-τ against CPIV3 and BPIV3 infection in MDBK cells was evaluated using different treatment routes at different infection times. The results showed that CPIV3 infection inhibited the production of type I IFNs, whereas exogenous goat IFN-α induced various ISGs, the IFN-τ encoding gene, and a negligible inflammatory response. Consequently, goat IFN-α prophylaxis but not treatment was found to effectively modulate CPIV3 and BPIV3 infection; the protective effect lasted for 1 week, and the antiviral activity was maintained at a concentration of 0.1 μg/mL. Furthermore, the antiviral activity of goat IFN-τ in response to CPIV3 and BPIV3 infection is comparable to that of goat IFN-α. These results corroborate that goat IFN-α and IFN-τ exhibit prophylactic activities in response to ruminant respiratory viral infection in vitro, and should be further investigated for a potential use in vivo.

Caprine parainfluenza virus type 3 N protein promotes viral replication via inducing apoptosis

Caprine parainfluenza virus type 3 (CPIV3) is one of the most important viral respiratory pathogens of goat. Accumulating evidence demonstrates that apoptosis is a cellular mechanism for the host response to pathogens, and it participates in regulating viral replication. However, there is little study on CPIV3-induced host cells apoptosis. In this study, primary goat tracheal epithelial (GTE) cells were established as a cellular model that is permissive to CPIV3 infection. Then, we showed that CPIV3 infection induced apoptosis in GTE cells, as determined by morphological changes, flow cytometry and TUNEL assay. Moreover, Caspase activity and the expression of pro-apoptotic genes further suggested that CPIV3 induced apoptosis by activating both the intrinsic and extrinsic pathways. Mechanistically, the ability of CPIV3 to induce apoptosis was activated by N protein, and the viral protein increased CPIV3 replication through effecting apoptosis. Overall, our findings showed that GTE cells that will enable further analysis of CPIV3 infection and offers novel insights into the mechanisms of CPIV3-induced apoptosis in host cells.

Screening interferon antagonists from accessory proteins encoded by P gene for immune escape of Caprine parainfluenza virus 3

The Caprine parainfluenza virus 3 (CPIV3) is a novel Paramyxovirus that is isolated from goats suffering from respiratory diseases. Presently, the pathogenesis of CPIV3 infection has not yet been fully characterized. The Type I interferon (IFN) is a key mediator of innate antiviral responses, as many viruses have developed strategies to circumvent IFN response, whether or how CPIV3 antagonizes type I IFN antiviral effects have not yet been characterized. This study observed that CPIV3 was resistant to IFN-α treatment and antagonized IFN-α antiviral responses on MDBK and goat tracheal epithelial (GTE) cell models. Western blot analysis showed that CPIV3 infection reduced STAT1 expression and phosphorylation, which inhibited IFN-α signal transduction on GTE cells. By screening and utilizing specific monoclonal antibodies (mAbs), three CPIV3 accessory proteins C, V and D were identified during the virus infection process on the GTE cell models. Accessory proteins C and V, but not protein D, was identified to antagonize IFN-α antiviral signaling. Furthermore, accessory protein C, but not protein V, reduced the level of IFN-α driven phosphorylated STAT1 (pSTAT1), and then inhibit STAT1 signaling. Genetic variation analysis to the PIV3 accessory protein C has found two highly variable regions (VR), with VR2 (31-70th aa) being involved in for the CPIV3 accessory protein C to hijack the STAT1 signaling activation. The above data indicated that CPIV3 is capable of inhibiting IFN-α signal transduction by reducing STAT1 expression and activation, and that the accessory protein C, plays vital roles in the immune escape process.

Viperin protein inhibits the replication of caprine parainfluenza virus type 3 (CPIV 3) by interaction with viral N protein

Caprine parainfluenza virus type3 (CPIV3) is a newly identified member of Paramyxoviridae family. CPIV3 is highly prevalence in China and showed pathogenicity to goats; in addition, CPIV3 infection causes severe clinical disease under stress and/or co-infection conditions. Viperin is one of the hundreds of interferon-stimulated genes (ISGs), and possesses a wide range of antiviral activities. The aim of this study was to systemically explore the anti-CPIV3 activity of ruminants' Viperin. CPIV3 infection up-regulated Viperin transcription but not protein expression in MDBK cells. Bovine and caprine Viperin genes (bVi and gVi) were amplified and analyzed by BLAST and multiple alignment. The obtained bVi/gVi amino acid sequences showed 99.5%-100% identity with previously submitted sequences and has variants at N-terminal domain (1-70aa) between each other. The pcDNA3.1 plasmids containing bVi and gVi genes were constructed to over-express the target proteins. CPIV3 was inoculated in MDBK cells over-expressing bVi/gVi and viral load was detected by qRT-PCR, virus titration and Western blot. Both of the bVi and gVi significantly inhibited CPIV3 genome copy numbers and viral titers at 24 and 48 hpi (P < 0.01); and viral N protein expression was also decreased, comparing with those of mock transfected group. The last 50aa C-terminal region was crucial for its anti-CPIV3 activity. In addition, the over-expression of bVi/gVi did not influence CPIV3 binding, entry and release in the cells. These results indicated the anti-CPIV3 activity occurred in viral RNA/protein synthesis progress of the viral replication cycle. The Viperin also showed similar inhibitory effect on different CPIV3 strains. The potential interaction of Viperin with viral proteins (N, P, C and V) was determined by confocal laser scanning microscopy and Co-IP assay. Co-localization of Viperin with N, P or C, but not V, was observed; while only N protein direct interacted with Viperin in Co-IP test, no matter using viral protein expressing plasmids transfected or CPIV3 infected cell samples. In conclusion, the bVi and gVi Viperin effectively inhibited CPIV3 replication potentially via the interaction of Viperin with viral N protein. The present results gave more information about antiviral activity of ruminants Viperin and provided foundation for further studies of the interaction of Viperin with CPIV3 and other related viruses.

Cholesterol-rich lipid rafts both in cellular and viral membrane are critical for caprine parainfluenza virus type3 entry and infection in host cells

Cholesterol-rich lipid rafts have been shown to play important roles in the life cycle of various non-enveloped and enveloped viruses. Deletion of cholesterol from lipid rafts could influence different steps of viral replication cycle including entry, infection, assembly and release. Caprine parainfluenza virus type3 (CPIV3) is a newly identified member of Paramyxoviridae family. CPIV3 is highly prevalence and threatened the goat industry in China. The infection mechanism of CPIV3 is under exploring and still not fully understood, the roles of cholesterol and lipid rafts for CPIV3 infection remains unclear. In this study, we investigated the association of cholesterol and lipid rafts with CPIV3 during the different viral replication stages (binding, entry and infection) in two cells [MDBK and goat bronchial epithelial (GBE) cells]. Methyl-β- cyclodextrin (MβCD) was used to deplete cholesterol from cell and viral membranes. The results showed that MβCD treatment significantly inhibited CPIV3 entry and infection in these two cells with a dose-dependent manner, but didn't impair the binding of CPIV3. Addition of exogenous cholesterol to the cells after MβCD treatment restored the viral infection. In addition, treatment of MβCD only before virus-entry showed inhibitory effect in MDBK cells. Depletion of cholesterol from virion envelop also decreased the entry and infection of CPIV3 in the two cells. Furthermore, lipid rafts isolation test indicated that viral proteins (HN and N) co-localized with lipid rafts during infection in MDBK and GBE cells. Viral N protein co-localized with caveolin-1 (the marker of lipid rafts) in these two cells both at the entry and infection steps, as detected by con-focal laser scanning microscopy test. In conclusion, the results presented here demonstrated that cholesterol rich lipid rafts play an important role in CPIV3 life cycle. The findings give new insights on understanding of the mechanism of CPIV3 infection and provide a new anti-CPIV3 strategy.